package chapter6;

/**
 * 缓存实例的不可变类
 */
class CacheImmutale {
    private static int MAX_SIZE = 10;
    private static chapter6.CacheImmutale[] cache = new chapter6.CacheImmutale[MAX_SIZE];

    private static int pos;
    private final String name;

    private CacheImmutale(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public static chapter6.CacheImmutale valueOf(String name) {
        for (int i = 0; i < MAX_SIZE; i++) {
            if(cache[i] != null && cache[i].getName().equals(name)) {
                return cache[i];
            }
        }
        if(pos == MAX_SIZE) {
            cache[0] = new chapter6.CacheImmutale(name);
            pos = 1;
        } else {
            cache[pos++] = new chapter6.CacheImmutale(name);
        }
        return cache[pos - 1];
    }

    @Override
    public boolean equals(Object obj) {
        if(this == obj) {
            return true;
        }
        if(null != obj && obj.getClass() == CacheImmutale.class) {
            CacheImmutale ci = (CacheImmutale)obj;
            return name.equals(ci.getName());
        }
        return false;
    }

    @Override
    public int hashCode() {
        return name.hashCode();
    }
}

public class CacheImmutaleTest {
    public static void main(String[] args) {
        CacheImmutale c1 = CacheImmutale.valueOf("aaa");
        CacheImmutale c2 = CacheImmutale.valueOf("aaa");
        System.out.println(c1 == c2);
    }
}
